As a kind of a technique that forms a film on a substrate, a plasma-enhanced atomic layer deposition (PE-ALD) method is known. In the PE-ALD method, the substrate is exposed to a precursor gas to chemically adsorb the precursor gas containing a constituent element of a thin film to be formed on the substrate. Subsequently, the substrate is exposed to a purge gas to remove the precursor gas excessively chemically adsorbed to the substrate. In addition, the substrate is exposed to plasma of a reaction gas containing the constituent element of a thin film to be formed so as to form a desired thin film on the substrate. In the PE-ALD method, the above-described processes are repeated, and as a result, a film processed by atoms or molecules contained in the precursor gas is generated on the substrate.
As a device that performs the PE-ALD method, a single substrate type film formation device and a semi-batch type film formation device are known. The aforementioned process of the PE-ALD method is repeated in a single processing chamber for the single substrate type film formation device. That is, in the single substrate type film formation device, the precursor gas is supplied into the single processing chamber, subsequently, the purge gas is supplied into the processing chamber, then, the reaction gas is supplied into the processing chamber, and plasma of the reaction gas is generated. Further, in the single substrate type film formation device, the purge gas is supplied into the processing chamber after generation of the plasma of the reaction gas and before subsequent supply of precursor gas. In the single substrate type film formation device, the supply of the precursor gas, the supply of the purge gas, the generation of the plasma of the reaction gas, and the supply of the purge gas need to be performed in sequence temporally as described above. Thus, a throughput becomes comparatively lowered.
Meanwhile, in the semi-batch type film formation device, a precursor gas-supplied region and a reaction gas plasma generation region are separately formed in the processing chamber and a substrate moves to pass through the regions in sequence. In the semi-batch type film formation device, the supply of the precursor gas and the plasma generation of the reaction gas may be simultaneously performed in different regions. Thus, a throughput is higher than that of the single substrate type film formation device.
Semi-batch type film formation devices are disclosed in Patent Documents 1 and 2 described below. The film formation device disclosed in Patent Document 1 includes a susceptor unit and a gas injection unit. The susceptor unit supports a substrate and is configured to rotate around a rotational axis. The gas injection unit is disposed to face the susceptor unit and includes a first region for supplying the precursor gas, a purge region for supplying the purge gas, a second region for supplying radicals of the reaction gas, and a separate purge region for supplying the purge gas. The first region, the purge region, the second region, and the separate purge region are arranged in a circumferential direction and exhaust lines extending in a radial direction are installed between the respective regions. The exhaust lines and the purge regions contribute to separating the first region and the second region. In the film formation device disclosed in Patent Document 1, respective angular ranges of the first region, the second region, and two purge regions extending in the circumferential direction with respect to the rotational axis are substantially the same as each other.
Further, the film formation device disclosed in Patent Document 2 includes a rotary tray, a shower head, and a plasma source. The rotary tray supports a substrate and is rotatable around a rotational axis. The shower head and the plasma source are disposed to face the rotary tray and arranged in the circumferential direction. The shower head has a substantially a fan-shaped planar shape and supplies a precursor gas. The plasma source is also has a substantially fan-shaped planar shape. The plasma source supplies a reaction gas, and supplies high-frequency power from a comb-type electrode to generate the plasma of the reaction gas. Exhaust ports are formed around the shower head and the plasma source and a shower plate is installed between the shower head and the plasma source to supply the purge gas. In the film formation device disclosed in Patent Document 2, the angular ranges of the shower head and the plasma source extending in the circumferential direction with respect to the rotational axis are substantially equal to each other and an angular range of the shower plate extending in the circumferential direction with respect to the rotational axis is significantly larger than the angular ranges of the shower head and the plasma source.